1. Field of the Invention
The present invention relates to American football, and more particularly to a more durable American football which is supported with construction liner for better supporting with lower manufacturing cost.
2. Description of Related Arts
American football is one of the most popular sports in United States. The conventional American football generally comprises a hollow outer ball carcass and an inflatable bladder disposed within the ball carcass for propping up the ball carcass after inflation. The inflatable bladder can be made of rubber or polyurethane when leather made ball carcass is used. The ball carcass of the American football comprises a plurality of cover pieces sewn edge to edge together to form an ellipsoidal shape. Each of the cover pieces comprises an outer cover skin and an inner liner for supporting between the outer cover and the inflatable rubber bladder. One of the most common materials of the outer cover skin is leather. Synthetic leather, such as polyvinyl chloride (PVC) or polyurethane (PU), is another common material for the outer cover skin because of its toughness nature that is more suitable for sewing. Besides, padded cover pieces are suggested in U.S. Pat. Nos. 4,462,590 and 4,660,831.
Generally speaking, if the ball carcass is made of leather, no backing is required. However, for polyvinyl chloride made ball carcass, woven fabric backing is attached on its inner surface for reinforcing and supporting. Also, for polyurethane made ball carcass, non-woven fabric is attached on its inner surface for reinforcing and supporting.
The liner of all the conventional American football can be of woven fabric, such as twilled nylon, cotton or other mixing material such as TC, TR, is preferably about 0.038 cm thick. To produce the conventional liner, a polyvinyl chloride or polyurethane layer and at least two lining layers are pressed to adhere on both sides of the polyvinyl chloride or polyurethane layer by feeding through a pair of pressing rollers to form a bolt of lining cloth. Pieces of inner liner with elliptical shape are cut from this lining cloth.
However, it is well known that the conventional American football is quite stiff to grip, catch and hold. It is because the inner liner, made of polyurethane and woven fabric layers adhered with each other, must be strong enough to support the softer outer cover skin to tolerate impact and to retain the ellipsoidal shape of the American football.
It is a main object of the present invention to provide an American football supported with improved construction liner which is made by vulcanization layers of rubber and fabric lining and is strong enough to provide a more durable American football with better supporting but lower manufacturing cost.
Another object of the present invention is to provide an American football wherein the stiffness and softness of the football can be designated by adjusting the thickness of the rubber piece of the construction liner thereof and/or the number of layers of the rubber piece and the fabric lining, so that different types of American football with different levels of softness and stiffness can easily be made for fitting different types of playground and different ages of players. For example, the American football for junior players may have softer ball carcass and the American football for professional players may have stiffer ball carcass.
In order to accomplish the above objects, the present invention provides an American football supported with construction liner, comprising a ball cover having a valve hole thereon and an inflatable bladder disposed within the ball cover for propping up the ball cover after inflation.
The inflatable bladder has a predetermined shape and a valve stem mounted hereon and extended through the valve hole of the ball cover. The ball cover comprises our elliptical cover pieces sewn edge to edge together. Each of the cover pieces comprises an outer elliptical cover skin made of leather or synthetic leather, such as polyvinyl chloride (PVC) or polyurethane (PU), and an inner elliptical construction liner which is overlappedly attached on an inside of the cover skin for supporting the cover skin and enclosing the inflatable bladder.
Each of the construction liners comprises a rubber piece of predetermined thickness vulcanizing with at least a fabric lining to form an integral liner piece having a size and shape at least equal to the outer cover skin.
The construction liner of each cover pieces of the ball cover of the American football according to the present invention is made by a specific method comprising the steps of:
(a) cutting a rubber sheet material into elliptical rubber pieces of a predetermined size;
(b) cutting a fabric sheet material into elliptical fabric linings having a same size of the rubber piece;
(c) compressing and vulcanizing each of the rubber pieces with one of the fabric linings together in a press mold, so as to firmly united the rubber piece with the fabric lining integrally to form a rubber-based fabric liner; and
(d) cutting each of the rubber-based fabric liners to a predetermined size.